Synchronous Message

A Synchronous Message in a UML Sequence Diagram represents a call where the sender waits for a response before continuing. In Modeldraw, you can use Synchronous Messages to show method invocations or requests that block the sender until a response is received.

A Synchronous Message and a Self-Call

Understanding Synchronous Message

A Synchronous Message represents a call where the sender waits for the receiver to handle the message. Key characteristics include:

• It shows a call that blocks the sender until a response is received

• It is drawn as a solid line with a filled arrowhead

• It typically triggers the start of an Activation Bar on the receiving Lifeline

• It is usually paired with a return message

A Synchronous Message is represented in UML by a solid line with a filled arrowhead pointing from the sender to the receiver.

Synchronous Messages are crucial in Sequence Diagrams for:

• Representing method calls or function invocations

• Showing interactions where the sender waits for a response

• Indicating the flow of control between objects

Creating a Synchronous Message

To create a Synchronous Message in Modeldraw:

1. Select the Synchronous Message tool from the toolbox

2. Click on the Activation Bar of the sending Lifeline where you want the message to start

3. Move your cursor to the receiving Lifeline

4. Click on the Activation Bar of the receiving Lifeline where you want the message to end

5. The Synchronous Message will be created between the two Activation Bars

Creating a Self-Call

To create a Self-Call in Modeldraw:

1. Select either the Synchronous Message or Asynchronous Message tool from the toolbox, depending on the type of Self-Call you want to create.

2. Click once on the Activation Bar where you want the Self-Call to start.

3. Click again on the same Activation Bar where you want the Self-Call to end.

4. The Self-Call will be created, represented by a looping arrow (solid for Synchronous, dashed for Asynchronous).